Despite growing recognition that individuals with comorbid psychiatric disorders constitute a very large subgroup with autism, there is a dearth of knowledge about this population, such as their developmental trajectories and adult outcomes. Most troubling is the lack of evidence-based treatment protocols and coordination of services to address their unique needs. The proposed research will address this critical gap in the literature by producing among the most comprehensive and integrative findings to date on common comorbidities in ASD and their relationship to multiple outcomes across development. Particular attention will be paid to possible moderating effects of existing treatments and services � medications, school services/accommodations, and insurance (type and level of coverage). To accomplish these research objectives, we will perform secondary data analysis on three large longitudinal datasets: PEELS, SEELS, NLTS-2. When combined, these datasets contain a nationally representative sample of individuals with ASD who received special education services, ages 3 to 26 (n=2,277). The findings of this study will inform parents, educators, professionals, and policy makers in their attempts to better understand this population and to provide evidenced-based treatments and school interventions that could steer this population onto optimal developmental trajectories and adult outcomes.